L20 PROCEEDINGS OF THE ACADEMY OF [1885. 



process of extrusion permits, it ascends until the small end of its 

 shell or siphon reaches the surface of the sand, so that it may 

 respire the water freely. In this position it remains until the 

 spawning is completed, during which process the body is pro- 

 truded from its shell to a great extent. Only four or five of the 

 cells or capsules were observed to exist in the body of the female 

 at one time, which were closely compacted there, occupying little 

 space; but, after extrusion, each cell becomes enlarged in thick- 

 ness, being swollen by the introduction of water. During the 

 process of formation, the egg-case is forced upward, appearing in 

 the form of a loop above the sand, though no portion of the 

 parent is then visible. 



This species commences to spawn early in life. One egg-case 

 was observed, the cells of which were about a half inch in diam- 

 eter, the shell of the parent being only three and a half inches 

 long. If handled gently, when dug from the sand, the conch 

 does not withdraw its body into its shell ; but, if it is injured, it 

 will quickly eject all the egg-cells from its body, and close its 

 operculum. As only four or five of the egg-cells are found in the 

 body at one time, in the process of formation, it is presumed that 

 the whole series of cases require a long time in their develop- 

 ment. 



• May 12. 

 Mr. Thomas Meehan, Vice-President, in the chair. 



Twenty-four persons present. 



The manuscript diary of Wm. Bartram was presented to the 

 library by Mi-. .Meehan. It covers the period from 1802 to 1822, 

 and contains notes on meteorology and natural history, especialh' 

 ornithology. 



A paper entitled "A Review of the American Genera and 

 Species of Mullidae," by Edw. A. Hall and J. Z. McCaughan, 

 was presented for publication. 



May 19. 

 Mr. Edw. Potts in the chair. 

 Fifteen persons present. 



Erythrite, Genlliite and Cuprite from near rhiladelphia. — 

 Prof. H. Carvill Lewis stated that during the Saturday excur- 

 sions of his class in mineralogy, a number of new mineral Localities 

 had been discovered, three of which were of sufficient interest to 

 in- recorded. 



Erj thiute. — Erythrite, the beautiful and rare arsenate of cobalt, 

 not heretofore recorded .is occurring in North America, was 



